Interworking function for VoLTE outbound roaming SMS messaging

This non-provisional application is a continuation of and claims priority to currently pending U.S. patent application Ser. No. 17/872,237, filed Jul. 25, 2022 and entitled “Interworking Function for VoLTE Outbound Roaming.”

This invention relates generally to the field of Internet Protocol (IP) and telecommunications networks, specifically to interworking of voice over long-term evolution (VoLTE) and circuit-switched (CS) short message service (SMS) in an outbound roaming environment from a mobile operator.

Circuit switch (CS) voice is a common technology that provides voice and SMS service to mobile network in a roaming environment. All 2G and 3G networks are using CS to provide voice and SMS service. To use CS for roaming, both visiting and home operators would need to equip with the CS network components (such as MSC, HLR) to provide both mobile-originated (MO) and mobile-terminated (MT) voice calls and SMS.

In 4G environment, a new technology known as “Voice Over LTE (VoLTE)” was invented to provide voice service in a long-term evolution (LTE, “4G”) network based on IP Multimedia Subsystem (IMS) technology and infrastructure. Both voice and SMS are supported over IMS.

With VoLTE and the IMS infrastructure, mobile network operators no longer need the CS infrastructure to provide voice and SMS service for their subscribers in the domestic (home) network. Many network operators are planning to shut down their 2G/3G network infrastructure to save the frequency bands for 4G and 5G services, as well as to reduce the operation and maintenance costs.

However, the prerequisite for using VoLTE roaming is that the home operator needs to have VoLTE roaming agreement with the visiting operator. Unfortunately, this is not very common. Many visiting operators either do not have the IMS infrastructure, or they do not want to provide VoLTE roaming to subscribers to protect their voice and SMS roaming revenue. This creates a problem for home operators wishing to implement VoLTE roaming. Thus, these mobile providers cannot shutdown their 3G roaming network infrastructure. A similar problem arises with LTE-only operators who do not have 2G/3G infrastructure, preventing them from providing voice and SMS service to outbound roaming to visiting operators without VoLTE roaming.

In the current state of the art, there is a need for a method and a system for provide an interworking function (IWF) between VoLTE and circuit-switched voice and SMS service for outbound roaming.

The present invention pertains to an Interworking Function (IWF) for enabling outbound roamers to use circuit-switched voice and SMS service in a Visited Public Land Mobile Network (VPLMN) without the need for VoLTE roaming agreements with a Home Public Land Mobile Network (HPLMN) operators. The IWF behaves as Circuit Switched (CS) roaming toward the VPLMN and behaves as VoLTE roaming toward the HPLMN.

In an embodiment, the IWF includes the following functions: (1) Diameter Routing Agent (DRA) that intercepts and routes Diameter S6a/s6d messages between VPLMN Mobility Management Entity (MME) and HPLMN Home Subscriber Server (HSS); (2) a virtual Home Location Register (vHLR) that provides subscriber registration service to Mobile Switching Center (MSC) in VPLMN; (3) a virtual Mobility Management Entity (vMME) that performs LTE registration to the HSS at HPLMN; (4) a virtual Short Message Service Centre (vSMSC) that receives and routes Mobile-Originated SMS (MO-SMS) from mobile device, and delivers Mobile-Terminate SMS (MT-SMS) to mobile device; (5) a virtual Gateway Mobile Switching Center (vGMSC) that delivers Mobile-Terminated Calls (MT-Call) to user equipment (UE); (6) a Serving Gateway (SGW) that encapsulates IP packets to General Packet Radio Service Tunneling Protocol (GTP) tunnel towards Packet Data Network Gateway (PGW) in HPLMN; (7) a Interconnect Border Control Function (IBCF) that acts as a border controller to Public Switched Telephone Network (PSTN) connection.

In an embodiment, the DRA in the IWF intercepts the diameter Update-Location-Request (ULR) and Update-Location-Answer (ULA) messages between VPLMN Mobility Management Entity (MME) and HPLMN Home Subscriber Server (HSS) during 4G network attachment. The DRA replaces the MME hostname in the ULR message with the hostname of the vMME so that subsequent HSS-initiated messages (such as Cancel-Location-Request) will be received and processed by the vMME.

Upon a 4G Network Attachment, when the vHLR receives a MAP-Update-Location request from MSC/VLR, the vMME builds a Diameter Sha ULR request to HSS. Upon receiving the ULA, the vMME sends a Sh User-Data-Request (UDR) to the HSS to retrieve the Multimedia Telephony (MINITEL) services subscribed by the roamer. These MINITEL services is later used to construct the MAP-Insert-Subscriber-Data requests to the MSC/VLR as a response to the MAP-Update-Location request.

Upon a 3G Network Attachment, when the vHLR receives a MAP-Send-Authentication-Info request from MSC/VLR or Serving GPRS Support Node (SGSN), the vMME builds a Diameter Sha Authentication-Info-Request (AIR) message to HSS for authentication. When the vMME receives the Authentication-Info-Answer (AIA) message, the vHLR sends a MAP-Send-Authentication-Info response to the MSC/VLR or SGSN. When the vHLR receives a MAP-Update-Gprs-Location request from MSC/VLR, the vMME builds a Diameter Sha ULR request to HSS. Upon receiving the ULA, the vMME sends a Sh User-Data-Request (UDR) to the HSS to retrieve the Multimedia Telephony (MMTEL) services subscribed by the roamer. These MMTEL services is later used to construct the MAP-Insert-Subscriber-Data requests to the MSC/VLR as a response to a subsequent MAP-Update-Location request from MSC/VLR.

The vMME instructs the SGW to establish a GTP session with HPLMN PGW for the ‘ims’ Access Point Name (APN) which will be used to carry VoLTE voice and SMS traffic. Then then vMME instructs the SGW to send a SIP REGISTER request to the IMS core at HPLMN for IMS registration. The IMS core is configured to use the ‘Early IMS Authentication’ (Ref: 3GPP TS33.978 Section 6.1) which trusts the user traffic from the GTP tunnel and skips the ‘Multimedia-Authentication Request/Answer’ procedure. Alternately, the SGW of the IWF or the Proxy-Call Session Control Function (P-CSCF) in HPLMN IMS core inserts an ‘auth-done’ parameter in the SIP REGISTER request so that the Serving Call Session Control Function (S-CSCF) assumes authentication is completed (Ref: 3GPP T S24.229 section 5.4.1.2.2E).

Mobile-Originated (MO) voice call from mobile device is realized by the VPLMN MSC that receives the CS Call setup request from UE, and break-out to its PSTN provider. This follows the standard procedure of a MO voice call in a CS roaming situation. HPLMN is not involved unless Customized Applications for Mobile networks Enhanced Logic (CAMEL) trigger is activated at the visiting MSC.

Mobile-terminated (MT) voice toward the UE can be provided in the following manner: (1) MT call arrives at the HPLMN IMS core where the subscriber is IMS-registered. The IMS core routes the SIP INVITE to the UE (where its Contact header was previously registered in IMS core during IMS registration) via the PGW, SGW and vGMSC. (2) The vGMSC interrogates the vHLR with a MAP-Send-Routing-Info (SRI). (3) The vHLR interrogates the VPLMN MSC with a MAP-Provide-Roaming-Number (PRN) for the Mobile Station Roaming Number (MSRN). (4) With the MSRN receives from MSC, the vGMSC routes the call to the PSTN with the called party number (SIP request-URI and ‘To’ header) being the MSRN. (5) The call arrives at the VPLMN MSC (who assigned the MSRN number) who further routes the call to the UE with a CS Call Setup.

Mobile-Originated (MO) SMS is realized by: (1) The VPLMN MSC who receives the SMS submit request from UE via the Radio Access Network (RAN), and forwards the request to the vSMSC via MAP-MO-Forward-SM (MO-FSM). (2) The vSMSC converts the request into a SIP MESSAGE and routes it to the SGW, PGW, HPLMN IMS Core and IP Short Message Gateway (IPSMGW) in the Telephony Application Server (TAS). (3) The IPSMGW routes the SMS request to the local SMSC or SMS Gateway for delivery to the recipient.

Mobile-Terminated (MT) SMS is realized by: (1) The IPSMGW in the HPLMN receives the MT-SMS, and routes it to the IMS Core in a form of SIP IVIES SAGE request. (2) The IMS core routes the SIP IVIES SAGE request to the UE (where its Contact header was previously registered in the IMS core during IMS registration) via the PGW, SGW and vSMSC. (3) The vSMSC send a MAP-Send-Routing-Info-For-SM (SRI-SM) to the vHLR who replies with the VPLMN MSC address. (4) The vSMSC converts the SMS request into a MAP-MT-ForwardSM (MT-FSM) and sends it to the MSC. (5) The MSC delivers the SMS to the UE via the Radio Access Network (RAN).

In the following detailed description of the preferred embodiment, reference is made to the accompanying drawings, which form a part hereof, and within which specific embodiments are shown by way of illustration by which the invention may be practiced. It is to be understood that other embodiments may be utilized, and changes may be made without departing from the scope of the invention.

1 FIG. 10 50 60 50 60 provides a schematic depiction of an embodiment of the invention. An Interworking Function (IWF)is deployed between a Visited Public Land Mobile Network (VPLMN)and a Home Public Land Mobile Network (HPLMN). VPLMNis a Circuit-Switched (CS) network—e.g., 2G, 3G network where the HPLMNis a Packet-Switched (PS) network e.g. 4G Long Term Evolution (LTE) or 5G network. In the current state of the art, the HPLMN with a LTE only network does not have the infrastructure or capability to do CS roaming, and thus VoLTE roaming is mandatory. A major limitation of VoLTE roaming is that VPLMN and HPLMN must have a preexisting agreement with one another, making it impractical for many network providers.

20 50 60 20 60 50 60 50 In an embodiment, the present invention addresses this problem by providing IWFin communication with both VPLMNand HPLMN. IWFenables HPLMNto provide voice and SMS roaming services to a subscriber roaming in VPLMNwithout requiring HPLMNto have CS capability or a VoLTE roaming agreement with VPLMN.

20 50 20 60 60 20 30 50 IWFhas a virtual Home Location Register (HLR) and virtual GMSC and SMSC that behaves like CS roaming toward VPLMN. IWFalso has a virtual Mobile Management Entity (MME) for LTE roaming toward HPLMN. The IMS Core in HPLMNis utilized to receive mobile-terminated (MT) MT-voice and MT-SMS, and routes the requests to the IWF, into CS roamingto reach the UE roaming in VPLMN.

2 FIG. 70 80 90 50 70 60 50 50 50 80 90 100 110 depicts a roaming User Equipment (UE)establishing a connection to UTRANor EUTRANof VPLMN. UEis a subscriber of HPLMNroaming in VPLMN. As explained above VPLMNis a 3G CS network or 4G network supporting CS fallback. VPLMNcomprises the following components: a UTRAN(for 3G), EUTRAN(for 4G), a Mobility Management Entity (MME)and a Mobile Switching Center (MSC).

20 120 130 140 150 160 170 180 Next, IWFcomprising a Diameter Routing Agent (DRA), a virtual Home Location Register (vHLR), a virtual Short Message Service Center (vSMSC), a virtual Gateway Mobile Switching Center (GMSC), a virtual Mobility Management Entity (vMME), a Serving Gateway (SGW)and an Interconnect Border Control Function (IBCF).

60 190 200 210 220 230 240 210 HPLMNcomprises a Home Subscriber Server (HSS), a Short Message Service Center (SMSC), an IP Multimedia Subsystem (IMS) core, a Telephony Application Server (TAS), a Packet Data Network Gateway (PGW), and a Policy and Charging Rules Function (PCRF). The IMS corecomprises a Proxy-Call Session Control Function (P-CSCF), an Interrogating-Call Session Controi Function (I-CSCF), and a Serving-Call Session Control Function (S-CSCF), collectively designated P/I/S-CSCF,

20 50 60 120 20 100 50 190 60 120 100 190 120 120 160 100 190 IWFcommunicates with both VPLMNand HPLMN. DRAof IWFis communicatively connected to MMEof VPLMNand HSSof HPLMNover s6a interface. DRAis configured to intercept Update-Location-Request (ULR) and/or Update-Location-Answer (ULA) messages exchanged between MMEand HSS. DRAcan be configured to mediate the intercepted ULR/ULA messages. The DRAmediates the ULR message in a manner that the vMME(instead of the VPLMN MME) hostname is stored in the HSS.

130 20 110 50 20 130 50 130 130 130 vHLRof IWFcommunicates with MSCof VPLMNusing Mobile Application Part (MAP) protocol. IWFuses vHLRto establish a Circuit Switched (CS) connection with VPLMN. This is accomplished by the MSC/VLR triggering a MAP-Location-Update procedure with vHLRto update a Global Title (GT) address of MSC/VLR in vHLRso that in subsequent Mobile-Terminated (MT) voice calls and SMS messages, vHLRwill return the GT of MSC/VLR for UE.

170 20 230 210 310 250 20 260 170 230 210 210 250 270 280 SGWof IWFenables a GPRS Tunneling Protocol (GTP) connection with HPLMN PGWwhich is connected to the IMS Coreand PCRF. In this manner, UEis able to make a mobile-originated (MO) voice callwith CS technologies, and IWFtranslates it into Packet-Switch SIP/RTPvia SGW, PGW, and IMS Core. The IMS Corebreaks-out the MO voice-callto PSTNto reach the destination party.

170 20 300 290 180 SGWof IWFbridges MT-callto its PSTNvia an Interconnect Border Control Function (IBCF), thereby enabling MT-voice roaming service for the UE.

110 50 140 20 50 MSCof VPLMNand the vSMSCof IWFare connected via MAP/SS7. This connection enables VPLMNto use CS-based SMS submit and delivery technology to provide MO and MT SMS roaming service to UE.

Network Attachment

3 FIG. 20 70 105 50 130 130 160 190 190 160 130 105 depict signaling flows for 3G network attachment using IWF. UEsubmits a network attach request to the SGSNin VPLMN, which triggers a MAP-Send-Auth-Info request to the vHLR. The vHLRand vMMEtranslates it into a Diameter s6a Authentication-Info-Request (AIR) to the HSS. The HSSreplies with an Authentication-Info-Answer (AIA). The vMMEand vHLRtranslates it to a MAP-Send-Auth-Info result to the SGSN.

105 130 130 160 190 190 160 130 105 Next, the SGSNsends a MAP-Update-Gprs-Location request to the vHLR. The vHLRand vMMEtranslates it into a Diameter s6a Update-Location-Request (ULR) to the HSS. The HSSreplies with an Update-Location-Answer (ULA). The vMMEand vHLRtranslates it to a MAP-Update-Gprs-Location result to the SGSN.

160 190 190 20 50 110 Next, the vMMEsends a Diameter Sh User-Data-Request (UDR) to the HSSto retrieve the subscriber's MINITEL telephony service subscription. The HSSreplies with a User-Data-Answer (UDA) with the MMTEL service subscription such as call forward and call barring. Such information is stored in the IWFfor constructing the Insert-Subscriber-Data request to the VPLMNMSC.

110 50 130 130 110 190 110 130 110 70 Next, the MSC/VLRin VPLMNsends a MAP-Update-Location request to the vHLR. The vHLRsend a MAP-Insert-Subscriber-Data request to the MSC/VLRwith the MINITEL service subscription retrieved from HSSin the previous step. The MSC/VLRreplies with MAP-Insert-Subscriber-Data result and the vHLRsends an MAP-Update-Location result to the MSC/VLRto complete the network registration to the UE.

20 170 230 240 230 170 Next, the IWFtriggers its SGWto establish a Packet Data Protocol (PDP) context and GTP tunnel for ‘ims’ APN by sending a GTP-C Create-Session-Request. This GTP tunnel is used to carry the voice and SMS traffic later. The PGWsends a Gx Credit-Control-request (CCR) to the PCRFwho replies with Credit-Control-Answer (CCA). The PGWsend a GTP-C Create-Session-Response to the SGWand PDP context setup is completed.

20 170 230 230 170 190 20 170 20 220 170 3 FIG. Next, the IWFtriggers SGWto send a SIP REGISTER request to the IMS core via PGWto register a virtual UE in the IMS domain. This registration is needed so that the IMS core will route MT-voice and SMS to the virtual UE via the PGWand SGW. The IMS core authorizes the subscriber registration by sending a Cx User-Authorization-Request (UAR) to the HSS, who replies with a User-Authorization-Answer (UAA). In the embodiment in, the IMS core performs an ‘Early IMS Authentication’ by trusting the SIP REGISTER request from the IWFSGW. The IWFtriggers the Telephony Application Server (TAS)to retrieve subscriber MMTEL profile using Sh User-Data-Request/Answer (UDR/UDA). The SIP registration is completed by the IMS core sending a 200 OK to the SGW.

170 20 210 60 210 In another embodiment, the SGWof the IWFor the P-CSCFof the HPLMNIMS core inserts an ‘auth-done’ parameter in the SIP REGISTER request so that the Serving Call Session Control Function (S-CSCF)assumes authentication is completed.

4 FIG. 20 70 100 50 190 120 20 190 depict signaling flows for 4G network attachment using IWF. UEsubmits a network attach request (for combined EPS/IMSI attachment) to the MMEin VPLMN, which triggers a Diameter s6a Authentication-Info-Request (AIR) to the HSS. This request is intercepted by the DRAin IWF. The HSSreplies with an Authentication-Info-Answer (AIA).

100 190 120 20 120 100 160 160 190 Next, the MMEsends a Diameter s6a Update-Location-Request (ULR) to the HSS. This request is intercepted by the DRAin IWF. The DRAmediates the request to replace the MMEhostname with the vMMEhostname so that subsequent HSS-initiated requests (such as Cancel-Location) will reach the vMME. The HSSreplies with an Update-Location-Answer (ULA).

100 171 Next, the MMEtriggers its SGWto establish a Packet Data Protocol (PDP) context and GTP tunnel for the default internet-access APN by sending a GTP-C Create-Session-Request. This GTP tunnel is used to carry internet traffic and is not related to voice or SMS.

100 110 130 190 190 Next, following the combined EPS/IMSI attachment procedure, the MMEtriggers its MSCto send a MAP-Update-Location request to the vHLR. The vHLR/vMME translates it into a Diameter s6a Update-Location-Request (ULR) to the HSS. The HSSreplies with an Update-Location-Answer (ULA).

160 190 190 20 110 Next, the vMMEsends a Diameter Sh User-Data-Request (UDR) to the HSSto retrieve the subscriber's MINITEL telephony service subscription. The HSSreplies with a User-Data-Answer (UDA) with the MMTEL service subscription such as call forward and call barring. Such information is stored in the IWFfor constructing the Insert-Subscriber-Data request to the VPLMN MSC.

130 110 190 110 130 110 70 Next, the vHLRsends a MAP-Insert-Subscriber-Data request to the MSC/VLRwith the MMTEL service subscription retrieved from HSSin the previous step. The MSC/VLRreplies with MAP-Insert-Subscriber-Data result and the vHLRsends an MAP-Update-Location result to the MSC/VLRto complete the network registration to the UE.

20 170 230 240 230 170 Next, the IWFtriggers its SGWto establish a Packet Data Protocol (PDP) context and GTP tunnel for ‘ims’ APN by sending a GTP-C Create-Session-Request. This GTP tunnel is used to carry the voice and SMS traffic later. The PGWsends a Gx Credit-Control-request (CCR) to the PCRFwho replies with Credit-Control-Answer (CCA). The PGWsend a GTP-C Create-Session-Response to the SGWand PDP context setup is completed.

20 170 230 230 170 190 20 170 20 220 170 3 FIG. Next, the IWFtriggers SGWto send a SIP REGISTER request to the IMS core via PGWto register a virtual UE in the IMS domain. This registration is needed so that the IMS core will route MT-voice and SMS to the virtual UE via the PGWand SGW. The IMS core authorizes the subscriber registration by sending a Cx User-Authorization-Request (UAR) to the HSS, who replies with a User-Authorization-Answer (UAA). In the embodiment in, the IMS core performs an ‘Early IMS Authentication’ by trusting the SIP REGISTER request from the IWFSGW. The IWFtriggers the TASto retrieve subscriber MMTEL profile using Sh User-Data-Request/Answer (UDR/UDA). The SIP registration is completed by the IMS core sending a 200 OK to the SGW.

170 20 210 60 210 In another embodiment, the SGWof the IWFor the P-CSCFof the HPLMNIMS core inserts an ‘auth-done’ parameter in the SIP REGISTER request so that the Serving Call Session Control Function (S-CSCF)assumes authentication is completed.

MO-Voice Service

5 FIG. 70 70 100 110 290 110 70 290 110 70 depicts a signaling diagram for a Mobile-Originated (MO) voice call from UE. UEsends a Call Control (CC) Setup to MSC, who replied with CC Call Proceeding, and checks for supplementary service (such as call barring). The MSCbreaks out the call by sending an ISDN User Part (ISUP) Initial Address Message (IAM) to the PSTN, who answers with Address Complete Message (ACM). The MSCsends a CC Call Alerting to the UE. The call is routed to the destination and the PSTNreplies with an ISUP Answer Message (ANM). The MSCsends a CC Connect to the UE.

70 110 290 70 290 110 70 110 MO-call is dropped when the UEsends a CC Disconnect to the MSC, which sends an ISUP Release (REL) to the PSTNand replies to UEwith a CC Release signal. The disconnect signal reaches the destination party. PSTNreplies with an ISUP Release Complete (RLC), and the MSCsends a CC Release Complete to the UE. The MSCgenerates CDR for billing.

50 110 Normally, the entire signaling flow happens in the VPLMNand HPLMN is not involved, when an exception when Customized Applications for Mobile networks Enhanced Logic (CAMEL) triggers is activated in the MSCfor the subscriber.

MT-Voice Service

6 FIG. 70 60 230 170 150 150 130 130 50 110 110 150 295 295 50 110 70 70 110 295 180 150 183 170 230 220 210 240 240 230 230 170 230 240 depicts a signaling diagram for a Mobile-Terminated (MT) voice call toward UE. MT call arrives at the HPLMNIMS core where the subscriber is IMS-registered. The IMS core routes the SIP INVITE to the UE (where its Contact header was previously registered in IMS core during IMS registration) via the PGW, SGWand vGMSC. The vGMSCinterrogates the vHLRwith a MAP-Send-Routing-Info (SRI). The vHLRinterrogates the VPLMNMSCwith a MAP-Provide-Roaming-Number (PRN) for the Mobile Station Roaming Number (MSRN). When the MSRN receives from MSC, the vGMSCroutes the call (SIP INVITE) to the PSTNwith the called party number (SIP request-URI and ‘To’ header) being the MSRN. The PSTNtranslates the SIP call into a CS call. The CS call arrives at the VPLMNMSC(who assigned the MSRN number) who further routes the call to the UEwith a CC Setup. The UEreplies with a CC Call Confirmed, followed by a CC Alerting. The MSCsends an ISUP Address Complete (ACM) to the PSTN. The IBCF/vGMSC (/) receives the SIPSession Progress and is populated to the SGW, PGW, IMS core and TAS. The P-CSCFof the IMS core triggers the PCRFto establish a dedicated bearer by sending a Rx AA-Request (AAR), and the PCRFsend a Gx Re-Auth-Request (RAR) to the PGW. The PGWcompletes the dedicated bearer setup by sending a GTP-C Create-Bearer-Request to the SGW, who replies with Create-Bearer-Response, PGWreplies with Gx Re-Auth-Answer (RAR), PCRFreplies with Rx AA-Answer (AAA).

70 110 295 295 200 180 150 170 230 220 When the user answers the call on the UE, it sends a CC Connect to the MSC, who translates it into an ISUP Answer Message (ANM) to the PSTN. The PSTNsends a SIPOK to the IBCF/vGMSC (/), which populates to the SGW, PGW, IMS core and TAS.

70 110 170 230 210 270 The voice payload is bridged at UE, MSC, PSTN, IBCF, vGMSC, SGW, PGW, P-CSCF (of the IMS core)and HPLMN PSTN.

270 220 230 170 150 180 295 295 110 70 70 110 295 295 200 170 230 220 170 230 230 240 240 210 170 In the embodiment, the remote party disconnect the call by the PSTNsending a SIP BYE, which populates to the IMS core, TAS, PGW, SGW, vGMSC, IBCFand PSTN. The PSTNsend an ISUP Release (REL) to the MSC, who sends a CC Disconnect signal to the UE. The UEreplies with a CC Release, and the MSCsend an ISUP Release Complete (RLC) to the PSTN. The PSTNsends a SIPOK to the IBCF/vGMSC, which populates to the SGW, PGW, IMS core and TAS. The dedicated bearer is torn down by the GTP-C Delete-Bearer-Request between SGWand PGW, Gx Re-Auth-Request/Answer (RAR/RAA) between PGWand PCRF, and Rx Session-Termination-Request/Answer (STR/STA) between the PCRFand P-CSCFof the IMS-core. The MSC generates CS-based CDR for billing. The SGWalso generates PS-based CDR for billing.

MO SMS

7 FIG. 70 110 140 140 230 230 220 depicts how Mobile-Originated (MO) SMS can be realized. The UEsend a RP-DATA for SMS-SUBMIT to the MSC, who checks for the supplementary service (such as call barring), and sends MAP-MO-Forward-SM (MO-FSM) to the vSMSC. The vSMSCconverts the request into a SIP MESSAGE and routes it to the SGW, PGW, HPLMN IMS Core and IP Short Message Gateway (IPSMGW) in the TAS. The IPSMGW routes the SMS request to the local SMSC or SMS Gateway for delivery to the recipient.

230 170 140 140 110 70 70 110 140 140 200 170 230 220 When the SMS is delivered successfully or failed, the IPSMGW sends a SIP MESSAGE for SMS-STATUS-REPORT to the IMS Core, PGW, SGWand vSMSC. The vSMSCtranslates it into a MAP-MT-ForwardSM to the MSC, which sends a RP-DATA for SM-STATUS-REPORT to the UE. The UEreplies with RP-ACK to the MSC, which sends a MAP-MT-ForwardSM result to the vSMSC. The vSMSCtranslates it into a SIPOK and sends it to the SGW, PGW, IMS core and TAS.

8 FIG. 60 70 230 170 140 140 130 110 140 110 110 70 depicts how Mobile-Terminated (MT) SMS can be realized. The IPSMGW in the HPLMNreceives the MT-SMS, and routes it to the IMS Core in a form of SIP MESSAGE request. The IMS core routes the SIP MESSAGE request to the UE(where its Contact header was previously registered in the IMS core during IMS registration) via the PGW, SGWand vSMSC. The vSMSCsends a MAP-Send-Routing-Info-For-SM (SRI-SM) to the vHLRwho replies with the VPLMN MSCaddress. The vSMSCconverts the SMS request into a MAP-MT-ForwardSM (MT-FSM) and sends it to the MSC. The MSCdelivers the SMS to the UEby sending a RP-DATA SMS-DELIVER.

70 110 140 140 170 230 220 220 200 230 170 140 140 110 110 70 If SMS delivery report is enabled, the UEsends a RP-DATA for SMS-DELIVER-REPORT to the MSC, who sends MAP-MO-Forward-SM (MO-FSM) to the vSMSC. The vSMSCconverts the request into a SIP MESSAGE and routes it to the SGW, PGW, HPLMN IMS Core and IP Short Message Gateway (IPSMGW) in the TAS. The TASreplies with a SIPOK to the IMS core, PGW, SGWand vSMSC. The vSMSCtranslates it into a MAP-MO-ForwardSM result, and sends it to the MSC. The MSCsends a RP-ACK to the UE.

The present invention may be embodied on various platforms. The following provides an antecedent basis for the information technology that may be utilized to enable the invention.

Embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc.

The machine-readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any non-transitory, tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. Storage and services may be on premise or remote such as in the “cloud” through vendors operating under the brands, MICROSOFT AZURE, AMAZON WEB SERVICES, RACKSPACE, and KAMATERA.

A machine-readable signal medium may include a propagated data signal with machine-readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A machine-readable signal medium may be any machine-readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. However, as indicated above, due to circuit statutory subject matter restrictions, claims to this invention as a software product are those embodied in a non-transitory software medium such as a computer hard drive, flash-RAM, optical disk or the like.

Hardware equipment may be agnostic as to general computing or may be telecommunications-specific. Some equipment providers include those under the brands HUAWEI, CISCO SYSTEMS, NOKIA, and QUALCOMM.

Program code embodied on a machine-readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wire-line, optical fiber cable, radio frequency, etc., or any suitable combination of the foregoing. Machine-readable program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, C #, C++, Visual Basic or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. Additional languages like ERLANG (or Open Telecom Platform, OTP) may be used or scripting languages such as PYTHON, LUA and PERL.

Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by machine-readable program instructions.

Access Point Name (APN) refers to a gateway between a GSM, GPRS, 3G or 4G mobile network and another computer network, frequently the public Internet. The APN identifies the packet data network (PDN) that a mobile data user wants to communicate with. In addition to identifying a PDN, an APN may also be used to define the type of service.

Application Function (AF) is a logical element of the 3GPP policy and charging control (PCC) framework which provides session related information to the policy and charging rules function (PCRF) in support of PCC rule generation.

Attribute Value Pair (AVP) means an information element of a Diameter Protocol message. Each Diameter message will contain multiple AVPs, such as Destination-Host AVP, Subscription ID AVP, Server-Name AVP, Framed IP Address AVP and the like.

Diameter is an authentication, authorization, and accounting protocol for computer networks.

Diameter Routing Agent (DRA) is an element in a 3G or 4G (such as LTE) network that enables real-time routing capabilities so that messages are routed among the correct elements in a network. The DRA was launched by the 3GPP to address the increased Diameter signaling traffic and growing sophistication of 4G LTE networks.

Evolved Node B (eNB or eNodeB) is a base station terminating the air interface on the network side. It is responsible for all radio resource management. It is also responsible for allocation of user traffic to the downlink/uplink, security and relaying of higher layer NAS (Non-Access Stratum) signaling to the MME.

Evolved Universal Terrestrial Radio Access Network (EUTRAN) is the radio (air interface) access architecture for LTE.

Fully Qualified Domain Name (FQDN) is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS).

Gateway Mobile Switching Center (GMSC) is a function within a PLMN (Public Land Mobile Network). GMSC terminates the PSTN (Public Switched Telephone Network) signaling and traffic formats. It converts this to protocols used in mobile networks. For mobile terminated calls, GMSC interacts with the HLR (Home Location Register) to retrieve routing information.

General Packet Radio Service (GPRS) is a packet oriented mobile data standard on the 2G and 3G cellular communication network's global system for mobile communications (GSM).

GPRS Tunneling Protocol (GTP) is defined by 3GPP standards to carry General Packet Radio Service (GPRS) within 3G/4G networks.

HLR means Home Location Register which is a database that contains subscription data about subscribers authorized to use the GSM core network. The HLRs store details of every SIM card issued by the mobile phone operator.

Home Public Land Mobile Network (HPLMN) means the network in which a mobile subscriber's profile is held. Mobile users that roam on other networks (visiting) receive subscription information from the HPLMN.

HSS means Home Subscriber Service which implements HLR and Diameter signaling. The HSS is a central database that contains user-related and subscription-related information. The functions of the HSS include functionalities such as mobility management, call and session establishment support, user authentication and access authorization. The HSS is used in IMS and 4G while HLR is used in 2G and 3G.

IMS means IP Multimedia Subsystem, an architectural framework to standardize the delivery of voice and other multimedia services of IP packet-switched networks.

IMSI means International Mobile Subscriber Identity. It is a specification used to uniquely identify a subscriber to a mobile telephone service. It is used internally to a GSM network and is adopted on nearly all cellular networks. The IMSI is a 50-bit field which identifies the phone's home country and carrier and is usually fifteen digits. This 15-digit number has two parts. The first part is comprised of six digits in the North American standard and five digits in the European standard. It identifies the GSM network operator in a specific country where the subscriber holds an account. The second part is allocated by the network operator to uniquely identify the subscriber. For GSM, UMTS and LTE network, this number is provisioned in the SIM card and for CDMA2000 in the phone directly or in the R-UIM card (the CDMA2000 analogue to a SIM card for GSM).

Inbound Roaming means a subscriber of another network “visits” within the local (home) network but is able to use the local network to makes calls, send messages and the like. The inbound roaming service allows subscribers from other operators to access the local network and services.

Interconnect Border Control Function (IBCF) is a boundary control between various service provider networks, providing IMS network security in terms of signaling information. It enables communication between IPv4 and IPv6 SIP applications, controlling transport plane functions, network topology hiding, screening of SIP signaling, selecting an optimum signaling interconnect, and creation of charging data records.

Interrogating Call Session Control Function (I-CSCF) is responsible for onward routing of SIP messages to the appropriate S-CSCF (Serving CSCF) for a given subscriber. It is a key element in the IMS roaming methodology.

IP Short Message Gateway (IPSMGW) is an IMS application server handling SIP based messaging services for IMS subscribers.

Long-Term Evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA technologies.

Media Gateway (MGW) handles the media plane (voice) in a distributed switch.

Media Gateway Control Function (MGCF) facilitates call control, interfacing the PS domain to the circuit switched domain when interworking between the IMS and PSTN is necessary.

Mobile application part (MAP) is an SS7 protocol used to access the home location register (HLR), visitor location register (VLR), mobile switching center and other components of a mobile network infrastructure.

Mobile Switching Center (MSC) means the primary service delivery node for GSM/CDMA, responsible for routing voice calls and SMS as well as other services. The MSC connects and releases end-to-end connections, administers mobility and hand-over requirements during the call and oversees charging and real-time prepaid account monitoring.

Mobility Management Entity (MME) is a component standardized within the long term evolution (LTE) system. MME provides mobility session management for the LTE network and supports authentication, handovers and roaming between subscribers and other networks.

MSISDN means Mobile Station International Subscriber Directory Number which is provisioned to a mobile device subscriber for making calls. It is the mapping of the telephone number to the SIM card (or CDMA2000 directly in the hardware) in a mobile or cellular phone and is the number normally dialed to connect a call to the mobile device. A SIM card has a unique IMSI that does not change but the MSIDN can change in time (e.g., telephone number portability).

Outbound Roaming typically occurs when a subscriber travels to another country. That subscriber's home network has an agreement with the network he is visiting in the other country. This agreement permits the subscriber to use his mobile phone to make calls and send messages on this visiting network. The subscriber is “outbound roaming” with respect to his home network providers. Concurrently, in the view of the visited network, this subscriber is “inbound roaming.” In other words, the inbound roaming service allows subscribers from other operators to access the local network and services. The outbound roaming service allows subscribers from the local network to access another operator's network and services.

Packet Data Network Gateway (PGW) is used to allocate IP addresses to the user equipment during default bearer setup.

Policy and Charging Rules Function (PCRF) is the software node designated in real-time that supports service data flow detection, policy enforcement and flow-based charging.

Proxy Call Session Control Function (P-CSCF) is a SIP proxy that is the first point of contact for user equipment in a mobile network. All SIP traffic to and from the user equipment must go through the P-CSCF. It acts as the ingress and egress point to and from a service provider's IMS domain with respect to the IMS client.

Public Switched Telephone Network (PSTN) means a circuit switched network that is used primarily for voice communications worldwide.

S6a Interface is Diameter interface between MME and HSS in the LTE network providing messages and procedures for phone attachment.

Serving Call Session Control Function (S-CSCF) is the primary node in the IMS handling session control. Subscribers are assigned a S-CSCF for the duration of their IMS registration to facilitate routing of SIP messages.

Serving Gateway (SGW) routes and forwards user data packets. The SGW manages and stores UE contexts, e.g. parameters of the IP bearer service, network internal routing information.

Serving GPRS Support Node (SGSN) is a main component of the GPRS network, which handles all packet switched data within the network.

Session Initiation Protocol (SIP) is a protocol designed to establish, maintain and terminate multimedia sessions. SIP has been adopted as the main signaling protocol in different network architectures. This SIP is deployed in 3GPP IMS (IP Multimedia System).

Signal Transfer Point (STP) is a node in an SS7 network (2G and 3G) that routes signaling messages based on their destination point code in the SS7 network.

Telephony application server (TAS) means a component used in the core network of a telecom network operator to provide telephony applications and additional multimedia functions. TAS provides the service logic for invoking the media servers to provide the call progress tones and announcements. If the calls originate or terminate on the PSTN, the TAS provides SIP signaling to the MGCF to instruct the media gateways to convert the PSTN TDM voice bit stream to an IP RTP stream and to direct it to the Internet protocol (IP) address of the corresponding IP phone.

Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) means the radio technology used between mobile terminals and the base stations of 3G UMTS.

User Equipment (UE) means a mobile device connectable to a cellular telecommunications network.

Virtualized Mobility Management Entity (vMME) means a virtualized implementation of the main control plane entity of the network which maintains mobility state of user equipment in a network.

Visitor Location Register (VLR) means a database storing data about mobile phones that recently joined a particular area of a mobile operator's network. The VLR keeps track of roamed mobile phone subscribers and communications with the HLR to determine whether the mobile phone is a permanent or temporary subscriber.

Visited Public Land Mobile Network (VPLMN) means a network that a mobile subscriber roams on when leaving their Home Public Land Mobile Network (HPLMN).

The advantages set forth above, and those made apparent from the foregoing disclosure, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing disclosure or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.